Radio frequency (RF) transceivers and receivers can be found in numerous applications, particularly in the field of wireless communications and radar sensors. In the automotive sector, there is an increasing demand for radar sensors used in so-called “adaptive cruise control” (ACC) or “radar cruise control” (RCC) systems. Such systems may be used, for example, to automatically adjust the speed of an automobile so as to maintain a safe distance from other automobiles or other objects ahead.
Modern radar systems make use of highly integrated RF circuits, which may incorporate all core functions of an RF font-end of a radar transceiver in one single package (single chip transceiver). Such RF front-ends may include, inter alia, a voltage controlled oscillator (VCO), amplifiers such as power amplifiers and low noise amplifiers (LNAs), mixers, and analog-to-digital converters (ADC). Furthermore, the single chip transceiver may include a digital signal processor for digital post-processing of the received signal.
Radar applications used in automobiles are subject to various standards concerning road traffic safety, for example the functional safety standard ISO 26262 titled “Road vehicles—Functional safety”. To ensure the functional safety of a radar sensor, it is important to know whether the current state of the radar sensor allows a reliable distance and speed measurement. However, also in applications other than radar, reliability may be an issue.
Thus there is a need for RF transceivers or receivers having improved self-test capability to increase the reliability of the overall system.